Satoru Aizawa

CASE STUDIES OF SMART MATERIALS FOR CIVIL STRUCTURES

In this paper, three case studies intending to apply smart materials to civil structures are presented. The first one is a study of response control using piezoelectric actuators. Actuators are inserted into the bottom of a column to produce a bending moment force. A control algorithm using the model matching method is introduced, and this algorithm is checked in shaking table tests of a four story frame. The second one is damage sensing of a structural member, using electric resistance characteristics of shape memory alloys. The relationship between electrical resistance and strain of shape memory alloy wire is studied and the maximum strain of the specimen which is regarded as a structural member is estimated. The third one is an energy dissipation device using super-elastic characteristics of a shape memory alloy. A basic energy dissipation device model using nitinol wire is proposed. The energy dissipation capacity is investigated by device tests, and an analytical model is constructed based on the test results.

Active vibration control of frame structures with smart structures using piezoelectric actuators (Vibration control by control of bending moments of columns)

A smart structure was tested for active vibration control of frame structures in which the bending moment of the columns was controlled by stack-type piezoelectric actuators integrated into the columns. Excitation tests were carried out for a model of a four-storey building 3.7 m in height and 2000 kg in total weight in which thirty-two piezoelectric actuators were used for bending moment control. The actuators were installed in two ways: in one case eight actuators were attached to each column of the first storey, and in the other case four actuators were attached to each column of the first and second storeys. Two control strategies, a model-matching method and the control theory, were examined for the smart structure. The tests showed that the smart structure could effectively reduce the responses of the building model, and all combinations of actuator installation method and the control strategy yielded almost the same performance.

Method of applying floor vibration‐damping work and vibration‐damping floor device

A method of applying a floor vibration-damping work and a floor vibration-damping device supporting horizontally displaceably respective supports points of the floor structure on a fixed floor and supporting the other respective points of said floor structure on the fixed floor with a position restoring function relative to the horizontal displacement, as well as a triggering function and a damping function during said displacement.

Active vibration control of flexural-shear type frame structures with smart structures using piezoelectric actuators

To apply smart structures to buildings, a new vibration control strategy is proposed for flexural-shear type frame structures with smart structures using piezoelectric actuators. Actuators are incorporated in columns, and the response of the entire structure is reduced by control of the bending moment and axial force of the columns. Combined application of these two controls is performed by arrangement of actuators. Two control strategies were tested: one involves the use of a model matching method and the other is based on control theory. Excitation tests were conducted with a four-storey frame structure with a total weight of 2000 kg and a height of 3.7 m, having H-section steel beams incorporating actuators as columns. The effectiveness of combined use of bending moment control and axial force control of columns with smart structures was confirmed.

Active vibration control of frame structures of shear and bending type with smart structure using piezoelectric actuator

To apply smart structures to buildings, a new vibration control strategy is proposed for flexural-shear type frame structures with smart structures using piezoelectric actuators. Actuators are incorporated in columns, and the response of the entire structure is reduced by controlling the bending moment and axial force of columns. Combined application of these two control is performed by arrangement of actuators. Two control strategies were tested. One is model matching method and author is H(infinity) control theory. Excitation tests were conducted with a 4-story fame structure of total weight 2,000 kg and height 3.7 m having H-steels incorporating actuators as columns. Effectiveness of combined use of bending moment control and axial force control of columns with smart structures was confirmed.